Rectifying tube



March 2, 1937. J. G. w. MULDER ET AL 2,072,604

RECTIFYING TUBE Filed oct. 3, 1935 Patented Mar. 2, 1937 UNITED 'STATES PATENT OFFICE mm to N. v.' ramps cinema-mr. Eindhoven etherian Netherlands, aa-

Applitlon October 3, 1935, Setlll No. 43,429 In the Netherlands October ll, 1934 SClnlml.

Our invention relates to rectifying tubes and more particularly to ionic rectifying tubes having a plurality of anodes and a common incandescible cathode.

The term ionic rectii'ying tube" as used herein and in the claims is to be understood to mean a tube whose lling consists oi' one or more gases or vapors, or a mixture of gases and vapors and has a pressure from several microns to several l0 centimeters of mercury.

Rectifying tubes according to the invention are particularly suitable for use in battery-charging circuits, and we shall describe our invention in this connection; however their use is not limlted thereto.

According to the invention the anodes are located near to. and preferably symmetrically around a central cathode and some of the anodes are provided with means which increases their negative blocking potential with respect to other anodes.

The above symmetrical spacing of the anodes makes it possible to shape the tube as a simple solid of revolution. Furthermore all of the terminals can be conveniently grouped on one or the two ends of the tube. In either case the terminal connections can be made in a simpler manner to standard bases or the like.

The anodes and the cathode can be in such close spacial relation, as not to occupy more space than that occupied by the electrodes of an ordinary full-wave rectifying tube, and in addition a minimum internal voltage drop and a maximum efllciency can be obtained.

To increase the blocking potentialv of some of the anodes with respect to others, they may be provided with shielding means for example by surrounding same with an electrically-conductive sleeve provided with an aperture which has a smaller area than the front surface of the anode; the discharge towards the anode being limited to pass through said aperture.

For the same purpose, especially when high alternating voltage differences occur between the anodes, electrostatic screens may be used to prevent the passage of an arc discharge between the anodes.

The rectier tube according to the invention may be advantageously used in circuit arrangements in which each anode of the tube together with its resistance, load and winding oi the supply transiormer-which winding is preferably provided with taps and a switch for selecting the desired tap-forms an independent half-wave rectifying circuit; the only common portion of (Cl. S56-275) the individual circuits being that portion which is associated with the incandescible cathode. Such an arrangement provides for a simple electrical system, whereby each circuit can be simply laid out in accordance with its particular current 5 and voltage requirements. Furthermore, the danger of back discharges or mutual disturbances is reduced to a minimum. To prevent any magnetizing eflect of the rectied current on the transformer it is preferable that the phase of 10 the alternating voltage of the individual anode circuits be such, that the direction of the rectied current as it passes a plurality of transformer windings be reversed.

Thereby the direct current components passing 15 through the windings as a result of half-wave rectication neutralize each other, when the various circuits of the rectifier are simultaneously loaded and for a given power a small transformer can be used. 20

In order that the invention may be more clearly understood and readily carried into eilect, it will be more fully explained in connection with the accompanying drawing, in which:

Figure l is a partly sectionized view of a rec- 25 vtiiier tube according to the invention.

Figure 2 is a partly sectionized view of another tube according to the invention.

Fig. 3 is a circuit diagram employing the rectiiier tube shown in Fig. l. 3o

'I'he rectier tube shown in Figure l has a vitreous envelope forming presses 56 and 62 and containing four anodes, 3, 4, 5, and 6 arranged symmetrically around and at a small distance from a common incandescible cathode 2. 35

'I'he rectifier tube is provided on its end with caps 20 and I1 of insulating material carrying screw terminals I6 and i9 and plug pins 63, 64, 6l, and 68 respectively.

'Ihe anode 5 is formed of a cylindrically-shaped 40 block 51 oi carbonaceous material, for instance of graphite, and is supported from pinch 58 by a supporting rod 60 of conductive material surrounded by a tube 6I of insulating material; the rod 6l being electrically connected by a lead 45 59 to the terminal Il. 'I'he anodes 3 and 4, which are of similar construction to anode 5 and are supported in a similar manner from press 62,

Y are electrically connected by leads I3 and il to the pins 63 and 64 respectively. 50

'l'he incandesclble cathode 2 is supported from the press 62 by supporting rods 65 and 66 of conductive material which rods are electrically connected by leads II and I6 to pins 61 and Il respectively. u

to terminal I9 in a manner similar to that ex` plained in connection with anode 5.

Suitably supported vfrom a projecting portion 9 of the press 58 is a cap-shaped screen 1 of conductive material provided on its closed end with an aperture 8 centered with and having a smaller area than the front i'ace of the anode 6. 'I'he projecting portion 9 extends downwards to surround a large portion of the rear end of the anode 5.

The projecting portion 9 and screen 1 thus serve to screen the anode 5 whereby the discharge from cathode 2 must pass through the the negative blocking voltage of this anode is considerably increased over that loi anodes 3, 4,

and 5. The screen 1 is of small size and the entire assembly of anode 5 together with its screening means occupies no more space than do the lower voltage anodes.

In the tube shown in Fig. 1 the terminals for the incandescible cathode 2 and the anodes 3 and- 4 are located at the lower end of the tube, whereas the terminals for the anodes 5 and 5 are located at the upper end. This arrangement has the advantage that the base I1 may be a standard four-pin base and thus can be inserted into a standard socket. yIt is preferable to connect the anode or anodes used for the higher negative blocking potential to the terminals I8 or I9, as this provides a long insulating path between the terminals of the hightension anodes and the remaining terminals.

It may be advisable, particularly when the anode voltages are not too high, to locate all the anode terminals on the same end of the tube as are the terminals for the incandescible cathode,

in which case a standard six-prong base, and4 thus a standard socket, can be used.v

The tube may have a gaseous or vapor illling, for example argon at about 4 millimeters pressure, or argon at about 0.7 millimeter, together with a supply of mercury.

'I'he tube shown in Figure 2 issubstantially the same as that shown in Figure l, only the location of the anode 81 is exactly the same as that of the remaining anodes and a metal screen 90 prevents the occurrence of arcing between the anodes 51 and 81. 'I'hus the blocking potential of these anodes with respect to each other is materially increased. A cylindrical portion. 9| of the metal screen 9|! surrounds the cathode 2 and is connected at 92 to one of the supply conductors of the cathode 2. This meas-- re results in a substantial increase of the blocking voltage sustained by the discharge paths from the cathode to any of the anodes of the tube.

for use in various circuit arrangements, one of such circuit arrangements with a tube according to Fig. 1, which is for charging four batteries. 8|, 82, 88, and 84 of diiferent current capacities, being shown in Fig. 3.

aperture 8 to the front face of the anode 5, and

The tube shown in Figs. 1 and 2 is adapted y The circuit arrangement shown in Fig. 3 consists of a transformer C having a primary winding 22 connected through a two-pole switch 2| to a suitable alternating current supply, and

. four secondary windings 10, 1|, 12, and 18, each provided at one end with a plurality of taps. Arms 28, 24, 25, and.26 serve to select the desired tap of windings 10, 1I, 12, and 18 respectively.

The rectier tube B, which is schematically shown, is of the same construction as the tube shown in Fig. 1, and has its electrodes indicated by the same reference numerals as in Fig. l.

The incandescible cathode 2 has its ends connected to` a heating winding 14, provided either on the transformer A or on a separate heating transformer, and having a center tap connected through conductor to the positive terminals 48, 44, 45, and 45 of batteries 8|, 82, 83, and 84.

The winding 10 has one end connected through an ammeter 38 to the negative terminal 58 of battery 84, and is connected through arm 28 and a resistance 15 to the anode 8. By changing the position of arm 28 connection may be made to various taps on winding 1li and the alternating voltage applied to anode 8 can be changed.

Similarly to winding 10, one--end of winding 12 is connected through ammeter 85 to the negative pole 54 of battery 82 and through arm 25 and resistance 11 to anode 5.

rlhe winding 13 has one end connected through a resistance 18 to anode 5 and has its other end connected through arm 26 and ammeter 36 to the negative terminal 53 of battery 8|. In a similar manner one end of winding 1| is connected through resistance 16 to anode 4 and its other endr is connected through arm 24 and ammeter 84 to the negative terminal 55 of battery 28.

It should be noted that windings 10, 1|, 12, and 13 are so arranged on the transformer A that the rectied current components in windings 10 and 12 are opposite in direction to those in windings 7 and 13. This prevents any magnetization eifect on the transformer by the direct current components and thus a smaller transformer can be used for the same power.

Thus it is seen that there is an individual rectifying circuit for each of the anodes, which circuits have in common only that portion between the cathode 2 and the positive terminals of the batteries.

To charge batteries of widely varying current capacities, it is advisable to compute the individual rectifying circuits-either for the lower or at the higher voltage values-for different current values which current values are preferably made evenly progressive. This permits the batteries to be charged in distinct series according to their current capacities, and also allowsby selecting the proper tap on the transformer winding-the matching of individual charging circuits with the number of cells used in the various series.

The individual rectifying circuits can be calculated for any desired values, however in the present instance the rectifying circuits corresponding to anodes 3, 4, 5, and 5 are calculated to charge batteries having a minimum of 12, 12, 12, and 60 lead cells respectively, at charging currents of l, 2, 3 and 0.25 amperes respectively.

While we have described our invention in connection with speciilc examples and speciilc applications, we do not wish to be limited thereto, but desire the appended claims to be construed as broadly as permissible in view of the prior art.

What we claim is;

i. An ionic rectlfyins tube .comprising an envelope, an incandescible cathode. a plurality of anodes disposed in the same. discharge space with said cathode, said anodes being symmetrically mounted around said cathode and at equal distances therefrom, and means to increase 'the negative blocking voltage of o ne of 'said-.anodes to a value greater than that of the anodes.

2. An ionic rectii'ying tube comprising an envelope. an incandescible cathode, a plurality of an'- odesdisposedinthesamedischargespacewith said cathode and close thereto, said anodes being symmetrically mounted around said cathode and at equal distances therefrom, and a cupshaped member oi' electrically conductive material surrounding one of said anodes to increase the negative blocking voltage thereof. said member being providedvithan aperturecenteredwiththe front faeeofsaidanodeandhavinganarealessthan that ot the front face of the anode.

3. An ionic rectifying tube comprising an envelope, an incandescible cathode, a plurality of anodes in the vicinity of said cathode and in the same discharge space therewith, means to i'ucreasethev negative blocking voltage of one oi said anodes, a four-pin base secured to one end of said tube. leads connecting two of said anodes to two of the pins; and leads connecting said cathode to the other two pins. the remaining anodes being connected through the envelope at the other end oi the tube.

JOHANNES GIJSBERTUS WILHELM MULDER. DANIEL MARIE DUINKER. 

